There have been proposed a wide variety of pipe couplings using a rotary valve as a valve structure that opens and closes a fluid passage.
A conventional pipe coupling of this type is arranged as follows. A slide valve holder that rotatably supports a rotary valve member is provided in a tubular body constituting a female coupling member. The slide valve holder is kept in an advance position by a spring when a male coupling member is not connected to the female coupling member. When the male coupling member is connected to the female coupling member, the slide valve holder is retracted by the male coupling member. In response to the movement of the slide valve holder, the rotary valve member rotates from an open position for opening the flow path to a closed position for closing the flow path.
The slide valve holder is provided with a through-hole constituting the flow path. An annular valve seat is formed around the through-hole. The rotary valve member rotates between the open position and the closed position while sliding, at its outer peripheral surface, relative to the valve seat. In the open position, a through-hole formed in the rotary valve member aligns with the flow path, thereby opening the flow path. In the closed position, the through-hole is out of alignment with the flow path, thereby closing the flow path (Japanese Patent Application Publication No. 2004-176755).
When the rotary valve member is rotated, it slides relative to the valve seat. To reduce the sliding resistance encountered when the rotary valve member is rotated, a conventional technique proposes a pipe coupling in which the peripheral surface of the rotary valve member has an annular surface portion that sealingly engages the valve seat when the rotary valve member is in the open position, thereby preventing leakage of fluid from between the flow path and the through-hole aligned with each other at that time. The rest of the peripheral surface of the rotary valve member is smaller in radius than the annular surface portion. With this structure, the conventional pipe coupling reduces the sliding resistance encountered when the rotary valve member is rotated (Japanese Patent Application Publication No. 2005-127377).
Patent Document 1: Japanese Patent Application Publication No. 2004-176755
Patent Document 2: Japanese Patent Application Publication No. 2005-127377